Saju: The Korean Four Pillars
Saju is the Korean version of the Chinese Four Pillars. The name literally means “four pillars”: the year, month, day and hour of birth. In Korea it is a living, mainstream practice, not an exotic curiosity: people drop by “saju cafés” as casually as they would see an astrologer in the West.
If the time is unknown, clear the field: the chart will be built without an hour pillar. Longitude and UTC offset are needed only if your city isn't on the list.
What the Calculation Shows
The chart is the same as in BaZi, but with Korean names: the stems and branches are labeled in Hangul and in Latin script, with the Chinese characters alongside.
- 사주팔자 (saju palja): the four pillars and eight characters — year, month, day and hour.
- 십신 (sipsin): the ten gods, the relationship of each stem to the Day Master, 일간 (ilgan).
- 대운 (daeun): ten-year Luck Pillars with the starting age, and 세운 (seun): the annual pillars.
- 신살 (sinsal): symbolic stars — 천을귀인, 문창귀인, 역마, 도화, 화개, 양인, 공망, 괴강살, 백호살, 홍염살, plus the 12 신살, the twelve spirits by the year branch.
- 원진 (wonjin) and 귀문관 (gwimungwan): Korean “warning” branch combinations within a chart.
- 오행 (ohaeng): the five elements, as a simple count and as percentages weighted by position strength.
- 신강 and 신약 (singang and sinyak): Day Master strength by the three classical signs: season, day branch, stems.
- 격국 (gyeokguk): the chart type by the month branch.
- 용신 (yongsin): the useful element, along with the helpful (희신) and unfavorable (기신) elements; based on them, each decade and each year is marked as favorable, mixed or difficult.
How the Method Works
Technically, saju is nearly identical to BaZi: the same ten Heavenly Stems, twelve Earthly Branches and sixty-year cycle. The year begins at Lichun, the month at the jie solar terms, and the day follows a continuous cycle. Some practitioners base the year and month on the lunar calendar instead — you can switch to it with the “Calendar” setting; the differences between the two versions are explained on the BaZi page.
The differences are in emphasis. The Korean tradition pays more attention to the ten gods: the relationships between the Day Master and the other characters of the chart, which describe roles such as helper, rival, resource, output, wealth and authority.
Birth Time in Korea
Korean Standard Time is UTC+9, set for the 135° E meridian. Seoul lies at 127° E, so solar noon there comes at around 12:30 by the clock. Korean practitioners usually shift the hour boundaries by half an hour: in Seoul the Rat hour runs from 23:30 to 01:30 by the clock.
The calculator does this more precisely, using the city's longitude and the equation of time. Historical quirks are covered too: in 1954–1961 Korea was on UTC+8:30, and in 1987–1988 it observed daylight saving time.
Saju Terms
| Term | Reading | Meaning |
|---|---|---|
| 사주팔자 | saju palja | four pillars and eight characters |
| 일간 | ilgan | Day Master, the stem of the day pillar |
| 십신 | sipsin | ten gods |
| 대운 | daeun | great luck, the ten-year pillars |
| 세운 | seun | luck of the year |
| 신살 | sinsal | symbolic stars |
| 공망 | gongmang | void |
| 신강 · 신약 | singang · sinyak | strong and weak Day Master |
| 격국 | gyeokguk | chart type |
| 용신 | yongsin | useful element |
| 기신 | gisin | unfavorable element |
| 원진 | wonjin | mutual resentment between branches |
| 궁합 | gunghap | comparing a couple's charts, calculated here |
How It's Used in Korea
Saju is traditionally consulted before a wedding (gunghap, comparing the bride's and groom's charts), when choosing a date for an important event, or when changing jobs. For many people it isn't about believing in predictions but a decision-making ritual and a chance to talk plans over with an outsider.
There are mobile apps and online services as well as traditional consultants. Many Koreans have consulted saju at least once, though far from all of them believe it works literally.
An Honest Look at the Method
Saju is a notable part of Korean culture and deserves to be treated as such. The method has no verifiable predictive power.
The practice of comparing charts before marriage deserves a separate mention: it can be useful as a prompt to talk about shared plans and harmful when the decision to marry is made based on the result. In Korea this is discussed openly.
Frequently asked questions
How is saju different from BaZi?
The calculation is the same: the same pillars, stems and branches. What differs is the names and the emphasis — the Korean tradition works in more detail with the ten gods and with a couple's compatibility.
Why does the Rat hour start at 23:30 in Korea?
Because of the difference between standard time and solar time: Seoul lies about half an hour west of its time zone's meridian. The calculator computes this correction from the city's longitude.
Can I calculate gunghap?
Yes, on a separate Gunghap page: the calculator compares the Day Masters, the spouse palaces, the useful elements for each other, the 원진 and 귀문관 combinations, and the spouse stars.